As noted in the last post, Azure Subscriptions can only have a direct trust relationship with a single Azure Active Directory tenant. The default tenant has a name that is derived from your email address, so my default Azure Active Directory tenant is mynewsecretprojectprotonmai.onmicrosoft.com which is fine as we can always add a custom domain to it, but we can do better with just a little bit of work. The steps are easy, and the instructions on the Microsoft site are excellent.
First, log into the Azure Portal and type subscription in the search box at the top and click on <subscriptions>
Now click on your subscription (note that you are the Owner
of the subscription, that is important!)
Click on <change directory>
Choose the new Azure Active Directory you want to move to and click <change>
and all that is left is the waiting. It can take a while, and doing this in other circumstances requires a ton of permission cleanup as all of your resources just changed which directory they trust. Since we don't have a ton of resources allocated, it doesn't take long until you get a notification that it is done
At this point it isn't really finished, it has just queued the operation. Let's check back tomorrow and see how it went.